Abstract

Aggregates make up between 80% and 90% of total volume or 94% to 95% of the mass of hot mix asphalt (HMA). For this reason, aggregate properties are very important. It directly affects the workability of the HMA. One of the properties of aggregate is coated surface area. The main objective of this study was to search the relationship of the surface area of aggregate, bitumen content, and extraction time in order to find the coated surface area of aggregate to be correlative with the optimum bitumen content. Three types of aggregate grading including dense grading, open grading, and gap grading that designed as ACW14, PA, and SMA14 were tested in accordance with the JKR Specification. A total of 45 specimens were prepared using Marshall Mix design method with three types of grading: ACW14 (dense graded), SMA14 (gap graded), and PA (open graded) in order to determine the optimum bitumen content (OBC). The second phase was to determine the coated surface area of aggregate by using the surface area factor. 45 samples were prepared and subjected to extraction of the bitumen content using NCAT ignition furnace to determine the time to remove bitumen from the aggregate in different types of mixes. Based on the results, it was observed that the bitumen content was significantly affected by the aggregate surface area while the aggregate surface area was influenced by the fine aggregate. Moreover, all of the observed parameters fitted highly to the linear relationship. Thus, it can be concluded that the bitumen content, aggregate surface area and the characteristics of bitumen have an influence on the extraction time.